This invention relates to a fuel-cell electric vehicle in which stopping of the operation of the vehicle is predicted to reduce residual water before the stopping in actuality.
The fuel cell generates electricity by electrochemical reaction between hydrogen and oxygen, and produces water at the same time. When the fuel cell is used under low-temperature conditions, product water remaining inside the fuel cell (residual water) would become frozen, which would deteriorate a membrane electrode assembly or MEA and lower its startup characteristics, thus significantly impairing its marketability for these or other reasons. Accordingly, a variety of proposals for improving a fuel cell system have been made such that residual water is reduced by a process of introducing a gas into a fuel cell (also called “scavenging process”) at a time when the fuel cell stops operating, in order to prevent the product water from becoming frozen in the fuel cell. See, for example, JP 2003-297399 A (FIG. 1).
However, typical scavenging processes used in a fuel cell system require a large amount of energy, for which electric power should be fed from a power source other than the fuel cell, such as a battery, thus increasing the size of the power source. In addition, such scavenging processes would produce noises. Consequently, the scavenging processes could disadvantageously impair the marketability.
The present invention has been made in an attempt to overcome the above disadvantages. In any case, it would be desirable to provide a fuel-cell electric vehicle in which the energy consumption and/or the noises in the scavenging process can be reduced.
Illustrative, non-limiting embodiments of the present invention overcome the above disadvantages and other disadvantages not described above. Also, the present invention is not required to overcome the disadvantages described above, and an illustrative, non-limiting embodiment of the present invention may not overcome any of the problems described above.